Answer the question below:

Question

The half-life of a radioactive element is the time it takes for 50% of its atoms to decay into something else. The half-life of radon-222 is about 3.8 days. About how many grams of radon-222 would remain a sample of 16 grams after 4 half-lives?

Answer 1

Each half-life reduces the amount by 1/2, so if you go through 4 half-lives, you reduce the starting amount to (1/2)^4 = 1/16

 

Amount remaining = (16 g) * (1/16) = 1 g